Cracking nipples, getting a deeper latch, flat nipples. Potential tongue tie

Hello! Above are just some of the issues I’m experiencing as a first time mom. My son is about 3 weeks old and has been slow to regain weight. We are getting him checked for a potential tongue tie. I have one flat nipple that has proven to be difficult. Both are also quite sensitive and pretty severely cracked that cause regular bleeding when trying to latch. I’ve tried nipple shields and nipple everters to try and encourage a deeper latch. If there is anyway to be seen soon to see what else can be done that would be great. Thank you, Ella